Optimal capacity placement for path restoration in STM or ATM mesh-survivable networks
TL;DR: A method for capacity optimization of path restorable networks which is applicable to both synchronous transfer mode (STM) and asynchronous transfermode (ATM) virtual path (VP)-based restoration and jointly optimizing working path routing and spare capacity placement.
Abstract: The total transmission capacity required by a transport network to satisfy demand and protect it from failures contributes significantly to its cost, especially in long-haul networks. Previously, the spare capacity of a network with a given set of working span sizes has been optimized to facilitate span restoration. Path restorable networks can, however, be even more efficient by defining the restoration problem from an end to end rerouting viewpoint. We provide a method for capacity optimization of path restorable networks which is applicable to both synchronous transfer mode (STM) and asynchronous transfer mode (ATM) virtual path (VP)-based restoration. Lower bounds on spare capacity requirements in span and path restorable networks are first compared, followed by an integer program formulation based on flow constraints which solves the spare and/or working capacity placement problem in either span or path restorable networks. The benefits of path and span restoration, and of jointly optimizing working path routing and spare capacity placement, are then analyzed.
Citations
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Patent•
14 Jul 2003
TL;DR: In this article, a path-segment-protecting p-cycle (flow p-cycles) is proposed to protect multi-span segments of contiguous working flow, not only spans that lie on the cycle or directly straddle it.
Abstract: This disclosure introduces a significant extension to the method of p-cycles for network protection. The main advance is the generalization of the p-cycle concept to protect multi-span segments of contiguous working flow, not only spans that lie on the cycle or directly straddle the p-cycle. This effectively extends the p-cycle technique to include path protection, or protection of any flow segment along a path, as well as the original span protecting use of p-cycles. It also gives an inherent means of transit flow protection against node loss. We present a capacity optimization model for the new scheme and compare it to prior p-cycle designs and other types of efficient mesh-survivable networks. Results show that path-segment-protecting p-cycles (“flow p-cycles” for short) have capacity efficiency near that of a path-restorable network without stub release. An immediate practical impact of the work is to suggest the of use flow p-cycles to protect transparent optical express flows through a regional network.
15 citations
TL;DR: This work introduces an architecture that provides differentiated protection services across multiple layers of network hierarchy that is very scalable in terms of communicating link-state and bandwidth information between adjacent layers.
Abstract: Metropolitan area and long-haul networks are migrating toward the deployment of optical mesh technologies. This requires, among other things, a new generation of highly intelligent protection and restoration mechanisms to perform functions of protection and bandwidth management. We introduce an architecture that provides differentiated protection services across multiple layers of network hierarchy. A connection at any client layer can request a protection against resource failures at any lower layer. A key aspect of the architecture is the hierarchical tree organization of shared risk link group (SRLG) resources. They represent routing-related failures across all layers of protocol stack. The architecture is very scalable in terms of communicating link-state and bandwidth information between adjacent layers. SRLG trees are used to aggregate this information and provide a summary to the client layer. We discuss the requirements and challenges for routing and signaling mechanisms in order to support the proposed architecture. The complexity of this architecture is evaluated and compared with the complexity of a nonhierarchical alternative.
15 citations
Additional excerpts
...Several algorithms based on integer linear programming (ILP), or heuristic have existed [4]–[7], [10]–[15]....
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TL;DR: A key theorem is proved according to which a facet of the k-node problem defined on the multigraph resulting from a k-partition is also facet defining for the larger problem under a mild condition.
Abstract: This paper considers the problem of designing a multicommodity network with single facility type subject to the requirement that under failure of any single edge, the network should permit a feasible flow of all traffic. We study the polyhedral structure of the problem by considering the multigraph obtained by shrinking the nodes, but not the edges, in a k-partition of the original graph. A key theorem is proved according to which a facet of the k-node problem defined on the multigraph resulting from a k-partition is also facet defining for the larger problem under a mild condition. After reviewing the prior work on two-partition inequalities, we develop two classes of three-partition inequalities and a large number of inequality classes based on four-partitions. Proofs of facet-defining status for some of these are provided, while the rest are stated without proof. Computational results show that the addition of three-and four-partition inequalities results in substantial increase in the bound values compared to those possible with two-partition inequalities alone. Problems of 35 nodes and 80 edges with fully dense traffic matrices have been solved optimally within a few minutes of computer time.
14 citations
Cites background from "Optimal capacity placement for path..."
...They refer to the work of Murakami and Kim (1995), Saito et al. (1998) and Iraschko et al. (1998) on this problem....
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10 Jun 2012
TL;DR: This paper presents an optimal and simple capacity placement and coding group formation algorithm that converts the sharing structure of any solution of a Shared Path Protection (SPP) technique into a coding structure with minimum extra capacity.
Abstract: Link failures in wide area networks are common and cause significant data losses. Mesh-based protection schemes offer high capacity efficiency but they are slow and require complex signaling. Additionally, real-time reconfiguration of a crossconnect threatens their transmission integrity. On the other hand, coding-based protection schemes are proactive. Therefore, they have higher restoration speed, lower signaling complexity, and higher transmission integrity. This paper introduces a coding-based protection scheme, named Coded Path Protection (CPP). In CPP, a backup copy of the primary data is encoded with other data streams, resulting in capacity savings. This paper presents an optimal and simple capacity placement and coding group formation algorithm. The algorithm converts the sharing structure of any solution of a Shared Path Protection (SPP) technique into a coding structure with minimum extra capacity. W e conducted quantitative and qualitative comparisons of our technique with the SPP and, another technique, known as p-cycle protection. Simulation results confirm that the CPP is significantly faster than the SPP and p-cycle techniques. CPP incurs marginal extra capacity on top of SPP. Its capacity efficiency is lower than the p-cycle technique for dense networks but can be higher for sparse networks. In addition, unlike p-cycle protection, CPP is inherently suitable for the wavelength continuity constraint in optical networks.
14 citations
Journal Article•
TL;DR: A framework is developed for jointly assigning wavelengths to service and restoration paths for all failures, for traffic patterns with single or multiple classes of protection.
Abstract: This paper considers capacity provisioning for service and restoration in a WDM optical network which provides lightpaths to higher layer networks. An optical network will likely serve several client networks with different protection requirements from the optical layer. In this paper, a framework is developed for jointly assigning wavelengths to service and restoration paths for all failures, for traffic patterns with single or multiple classes of protection. For various restoration methods, the problem is reduced to a vertex coloring problem in a graph. We present routing and wavelength assignment algorithms for service and restoration with varying capacity/restoration time tradeoffs, and evaluate their performance through simulations. We consider three different kinds of traffic patterns in terms of protection requirement: 100% protected traffic, mixed protected/unprotected traffic, and mixed protected/low-priority traffic. We quantify the capacity cost of protection in mixed traffic patterns as a function of the proportion A of the protected traffic in the mix, and identify the range of A where protection can be provided at low capacity penalties. This is important for assessing the economical feasibility of providing protection to a class of connections at the expense of reducing the amount of traffic that could be served without protection guarantees.
14 citations
Cites background or methods from "Optimal capacity placement for path..."
...This typically provides fast recovery from a failure, even though it is not as capacity efficient as path restoration [10,14,23]....
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...The service capacity assignment problem in optical networks [13,17], and the restoration problem in other networks such as ATM [10,23], SONET [22], have also been extensively studied....
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...1 which have been widely used as test networks in literature [10,17]: Network 1 (Arpanet with 20 nodes, 32 links), Network 2...
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...area network [10]....
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...The observations made in [10] from the integer programming solutions of the joint routing/restoration problem in ATM networks also support this intuition....
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References
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Book•
16 Feb 1970
TL;DR: Interestingly, integer programming and network flows that you really wait for now is coming, it's significant to wait for the representative and beneficial books to read.
Abstract: (1970). Integer Programming and Network Flows. Journal of the Operational Research Society: Vol. 21, No. 4, pp. 500-501.
638 citations
TL;DR: Self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN are proposed and high-speed restoration technique which exploits the benefits of the VP is proposed and described.
Abstract: This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed. >
233 citations
TL;DR: A comparative study of the effectiveness of KSP versus Max Flow as an alternative rerouting criteria in the context of transport network span restoration, and the hypothesis is made that a generalized "trap" topology is responsible for all KSP-Max Flow capacity differences.
Abstract: In the development of technologies for span failure restoration, a question arises about the restoration rerouting characteristics to be specified. In theory, maximal rerouting capacity is obtained with a maximum flow (Max Flow) criterion. However, rerouting that realizes the k-successively shortest link disjoint paths (KSP) may be faster, easier, and, in distributed implementation, more robust than a distributed counterpart for Max Flow. The issue is, therefore, what the restoration capacity penalty is if KSP is used instead of Max Flow. To explore this tradeoff, the authors present a comparative study of the effectiveness of KSP versus Max Flow as an alternative rerouting criteria in the context of transport network span restoration. The comparison applies to both centrally controlled and distributed restoration systems. Study methods include exhaustive span failure experiments on a range of network models, and parametric and analytical investigations for insight into the factors resulting in KSP versus Max Flow differences. The main finding is that KSP restoration capacity is more than 99.9% of that from Max Flow in typical network models. The hypothesis is made that a generalized "trap" topology is responsible for all KSP-Max Flow capacity differences. The hypothesis is tested experimentally and used to develop analytical bounds which agree well with observed results. These findings and data are relevant to standards makers and equipment developers in specifying and engineering future restorable networks. >
199 citations
NEC1
TL;DR: In order to achieve fast restoration, a distributed control mechanism that is applicable to both line and path restoration is proposed, and the shared use of spare channels for various failure scenarios, including multiple failure cases, are allowed.
Abstract: With the advent of networking technologies intelligent network elements, such as the digital cross-connect system (DCS), will make it possible to dynamically reconfigure a network for restoration purposes. Both restoration control of DCSs and spare-channel design issues are presented, and how they work together so that a fast and economical SONET self-healing network is obtained. In order to achieve fast restoration, a distributed control mechanism that is applicable to both line and path restoration is proposed. The proposed method allows the shared use of spare channels for various failure scenarios, including multiple failure cases, so that the efficient use of spare channels can be achieved. A linear-programming-based scheme is proposed to obtain spare-channel assignment, where a network-flow technique is used. Through a simulation study, a fast and economical self-healing network is verified. >
193 citations
"Optimal capacity placement for path..." refers background or methods in this paper
...Previous work used an IP approach based on -flow -cut considerations to solve the spare capacity placement problem in a span-restorable network [4], [11], [20]....
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...Issues related to the restoration mechanisms themselves are addressed in related works [1], [2], [4], [21], [27]....
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Proceedings Article•
01 Jan 1987
180 citations